Calculate the standard free energy of formation of mercury(II)oxide at 298 K,given A)+58.5 kJ.mol^-1 B)+117.1 kJ.mol^-1 C)-58.5 kJ.mol^-1 D)-123.1 kJ.mol^-1 E)-117.1 kJ.mol^-1

Question

Quizplus · Accepted Answer

The standard free energy of formation of a compound is given by the formula ΔG°f = ΣΔGf°(products) - ΣΔGf°(reactants). The chemical equation for the formation of mercury(II) oxide is 2Hg(l) + O2(g) → 2HgO(s), so the reactants are mercury and oxygen in their standard states. The standard free energy of formation for mercury and oxygen are both zero, so they do not contribute to the calculation. The standard free energy of formation for mercury(II) oxide is -58.5 kJ/mol, which is negative because the reaction is exothermic (i.e. it releases energy). Therefore, the correct answer is C.

Calculate the Standard Free Energy of Formation of Mercury(II)oxide at 298